If they have good technique from the get go then go with the program as rx'd.

If they have mobility issues then you may have to spend more time working with them on technique. Higher amounts of repetitions are definitely good in this case, and safer as you don't have to load up the heavy weights.

Add in the stuff you said and you have legit need for higher reps.

Also, if someone is developing sore joints (from overuse) then backing off to lighter high reps is also a good idea. Lighter work (8-15 reps) is very good for connective tissue rehab. Sometimes even more reps than that.

It all depends. If they can handle the lower reps right away and carry on for months I like that base first. You get a nice combo of strength + hypertrophy and then you can go from there whether you want to go whether more hypertrophy, athletics, strength, plifting, etc.